You should fill out the form using the same information that you used to register to vote. You will need to provide a mailing address (not a P.O. Box) if your ballot needs to reach you somewhere else. If you are traveling you can use the address of the hotel, office or a family member who will collect mail for you.
The U.S. Vote Foundation form is customized for your state. If your form has a place for a witness or notary, or proof, identification or disability, that is a requirement of your state you must comply with. If you need more information about your state's specifics you can go to the US Vote homepage, click on Election Official Directory. Choose your State and Region to find the link to your Local Elections Website. You can go to that site for more state specific information. If your region does not have a website, you will have to contact your local election official.